RU2251799C2 - Wireless communication systems - Google Patents

Abstract

FIELD: wireless communication systems.

SUBSTANCE: in one of possible implementation methods method includes stages of detection of fast fading in signal of straight communication line, informing gate about fast fading, and adjusting power control contour amplification coefficient therein, as functions of communication channel quality. In another implementation variant, method includes stages of detection of fast fading in check communication line in gate and adjustment of power control contour amplification coefficient, as functions of communication channel quality.

EFFECT: higher efficiency of method implementations.

8 cl, 6 dwg

Description

Technical field

The present invention relates to wireless communication systems. More specifically, the present invention relates to a new and improved system and method for power control in a wireless communication system.

State of the art

Wireless communication networks are notably popular in all aspects of business, industry and personal life. Portable, portable communication devices have been widely developed in recent years. Portable devices, such as cell phones, are widely used by both business and personal users. In addition, advanced systems, such as satellite communications systems using portable, portable and mobile phones, are currently being deployed.

In wireless communication systems, signals are subject to fading. Fading is caused by environmental factors that weaken the signal power when it is transmitted from the transmitter to the receiver. A quantitative characteristic of fading is provided by the measurement in the receiver of the signal-to-noise ratio (SNR) of the received signal. Systems have been developed to control the transmitted signal power to compensate for fading. One such system is known as a single-loop power control system.

In a single-loop power control system, the receiver monitors the SNR of the received signal and sends transmit power control commands to the transmitter to maintain a certain “threshold” SNR in the receiver. Conventional single-circuit power control systems typically use two or three types of such commands. One type of command tells the transmitter to increase transmit power. Another type of command tells the transmitter to reduce the transmitted power. The amount by which the transmitted power increases or decreases in response to such a command is defined as the loop “gain”. Some systems use a third type of command to indicate to the transmitter the need to maintain the transmitted power at the current level.

Single-loop power control works well in a transmission environment characterized by slow fading. With slow fading, there is no significant fading during the time, defined as the "period" of the circuit required for the power control command to arrive at the transmitter and measure the resulting signal-to-noise ratio at the receiver. One example of a slow fading transmission medium is a medium in which only thermal noise occurs as interference.

However, in a medium-speed fading signal transmission medium, single-loop power control becomes inadequate. In conditions of fading at an average speed, significant fading exists during one period of the contour. A possible example of a medium-speed fading transmission medium is when a transmitter or receiver quickly moves past stationary obstacles, causing rapid changes in signal attenuation. In such a medium-speed fading transmission medium, the threshold SNR may not be sufficient to guarantee signal quality. This is because the circuit is too inert to respond to rapid changes in the SNR of the received signal.

In digital communication systems, the adequacy of the threshold SNR can be quantified by the ratio of information bits received with errors to the total number of received bits. This ratio is usually recalculated for each frame. Thus, the calculated ratio is known as the "frame error rate" (FER) of the signal. A well-known type of system aimed at solving this problem is the so-called "dual-circuit" power control system.

In a dual-circuit power control system, the single-circuit power control system described above is used as an “internal” circuit. The SNR threshold used by the internal circuit is changed by the "external" circuit based on the received FER of the received signal. For example, when the FER rises above a predetermined FER threshold, the SNR threshold increases by a fixed predetermined amount. This process continues until the PSC falls below the SNR threshold.

One of the considerations taken into account in dual-circuit power control systems is the choice of a fixed gain used by the internal circuit. The choice of this gain is a compromise between two conflicting factors. In a medium-fading environment, a fast loop response is required. This requires a greater gain in the inner loop. With a large gain of the inner loop gain, smaller loop periods are required to change the threshold SNR by a larger amount. However, in an environment with slow signal fading, a large gain will result in large fluctuations in the SNR near the threshold SNR. These oscillations cause unnecessary power consumption of the transmitter. Therefore, a fixed internal loop gain is not suitable for applications in which the signal will experience both fast fading and slow fading.

In addition, fixed gain systems have difficulty in conditions characterized by fast signal fading. With fast fading, the SNR experiences several large fluctuations during one period of the external circuit (that is, the time required to adjust the SNR threshold based on one or more FER measurements). Fluctuations with fast fading typically have a frequency of the order of hundreds of hertz. In such a transmission medium, the reaction time of the inner loop is no longer fundamentally important, since the inner loop probably cannot track fading. There is a need for a dual-loop power control system in which the gain of the inner loop can be varied to match the fading rate.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus and method for controlling the power of a signal transmitted from a transmitter to a receiver to compensate for fading in a wireless communication system. In one embodiment, the method includes measuring steps in a first station of a signal-to-noise ratio for a signal transmitted by a second station; controlling the power of the transmitted signal as a function of loop gain, signal-to-noise ratio, and signal-to-noise ratio threshold; measurements in the first station of the quality of the received signal; adjusting the signal-to-noise ratio threshold as a function of signal quality and signal quality threshold; measuring the signal fading rate in the first station and adjusting the loop gain as a function of fading speed and the threshold of fading speed.

In one embodiment, the method includes the steps of measuring a signal to noise ratio in a first station for a signal transmitted by a second station; controlling the power of the transmitted signal as a function of loop gain, signal-to-noise ratio, and signal-to-noise ratio threshold; measurements in the first station of the quality of the received signal; adjusting the signal-to-noise ratio threshold as a function of signal quality and signal quality threshold; measuring in the second station the fading rate of the additional signal transmitted by the first station; and adjusting the loop gain as a function of fading speed and fading threshold.

One of the advantages of the present invention is that it reduces the effects of rapid fading.

Brief Description of the Drawings

The features, objectives and advantages of the present invention are explained below in the detailed description, illustrated by the drawings, which represent the following:

Figure 1 is a block diagram illustrating an example communication system;

FIG. 2 and FIG. 3 are block diagrams illustrating the transceivers of FIG. 1 in more detail;

4 is a flowchart depicting the operation of an internal power control loop, in accordance with a preferred embodiment of the present invention;

5 is a block diagram depicting the operation of an external power control loop, in accordance with a preferred embodiment of the present invention; and

6 is a flowchart depicting the operation of an internal loop with variable gain of a dual-loop power control, in accordance with a preferred embodiment of the present invention.

Detailed Description of Preferred Embodiments

The present invention relates to a device and method for dual-circuit power control in a wireless communication system. In a preferred embodiment, the present invention is used in a code division multiple access (CDMA) communication system. The power control loops operating in such systems are disclosed in US patent applications No. 09/164383 for “System and method for selecting power control modes” and 09/164384 for “System and method for optimized power control”, the rights to which are assigned to the assignee of the present invention, and incorporated into this description by reference. Other examples of power control methods in such communication systems are disclosed in US Pat. Nos. 5,383,219 to "Fast Power Control of a Direct Link in a Code Division Multiple Access System," January 17, 1995; 5396516 to "Method and system for dynamically changing control parameters in the transmitter power control system", dated March 7, 1995; and 5,267,262 to the "Transmitter Power Management System" of November 30, 1993, which are incorporated herein by reference.

I. An example of a transmission medium

Before describing the invention in more detail, it is useful to describe an example of the conditions under which the invention can be used. The present invention can be used in any wireless communication system, especially in a system in which it is desirable to control the amount of power generated by the transmitter. Such conditions include, without limitation, cellular communications systems, personal communications systems, satellite communications systems and many others.

1 is a diagram illustrating an example of a communication system 100. 1, system 100 has two transceivers 102 and 104. The transceiver 102 has a transmitter 106 and a receiver 108. The transceiver 104 has a transmitter 112 and a receiver 110. Data or other information is transmitted between the transceivers through a transmission channel 122. In satellite, cellular and other wireless communication systems, channel 122 is a wireless communication line. In satellite communications systems, channel 122 includes one or more satellite transponders. Channel 122 is a bi-directional channel that includes a “forward” signal 116 and a “return” signal 118.

In some operating conditions, channel 122 is a packet data channel in which data is transmitted as data packets. This often occurs when information is presented in the form of digital data. In other operating conditions, the analog data modulates the carrier frequency and is transmitted on channel 122.

In the example of a cellular communication system, the transceiver 102 is a portable or mobile cell phone, and the transceiver 104 is a base station in a local cell node that provides service in the current location area of the phone. In an example of a satellite communications system, the transceiver 102 is a portable, mobile, or stationary transceiver (e.g., a satellite telephone), and the transceiver 104 is located in the ground gateway. In the example of a satellite communications system, a satellite is used to transmit signals between transceivers 102 and 104 on channel 122.

The present invention is described in terms of these exemplary conditions of use. The description in these terms is provided for convenience only. It should be borne in mind that the invention is not limited to use in the above example. In fact, from the following description, it is obvious to a person skilled in the art how to implement the invention in alternative working conditions.

II. Power management

The present invention relates to a system and method for controlling the power of a transmitted signal to compensate for fast fading in a wireless communication system. With fast fading, several signal fading occurs during one period of the external circuit. Thus, the external circuit is ineffective to reduce rapid fading. Such fast fading often overlaps with the slower pattern of fading. The inventors have found that a good solution for the case of fast fading is to ignore the fast (high-frequency) component of fading, and instead track every slower (low-frequency) component of fading. According to the present invention, when fast fading is detected, the system attempts to track the main slow fading, rather than trying to track fast fading. In a preferred embodiment of the present invention, this is done using a small gain of the inner loop.

2 is a block diagram illustrating a transceiver 102 in more detail. The transceiver 102 includes a transmitter 106, a receiver 108, a measuring element 202, a processor 204, a memory 206, a data receiver 210, and a data source. In operation, the receiver 108 receives the signal 116 and transmits it to the data receiver 210. The data receiver 210 may be any element that uses data, such as a codec, modem, digital signal processor, and the like. Receiver 108 can perform certain tasks, such as demodulation, for signal 116, as is well known in the art.

The measuring element 202 performs certain measurements of the parameters of the signal 116, as described in detail below. These measurements, for example, include measurements of SNR, signal quality based on the presence of one or more error events (such as FER) and fading rate (SZ). In a preferred embodiment, the measuring element 202 includes an SNR measurement circuit 214 and a frame error measurement circuit 216. The SNR measurement circuit 214 receives the SNR measurement results of the received signal 116. The frame error measurement circuit 216 receives the error rate measurements or one or more other error events of the received signal 116. The circuits that perform these functions are well known in the art. These measurement results are transmitted to a processor 204, which may be any processor known in the art or developed in the future. The processor 204 uses memory 206 to store data, such as, for example, SNR, FER and SOC measurements, and other values, such as thresholds, for comparison with these measurement results.

A data source 212 generates data for transmission. Data source 212 may include elements such as codecs, modems, digital signal processors, and the like, well known in the art. A transmitter 106 receives data from a data source 212 and performs modulation. The processor 204 may be implemented using hardware, software, or a combination thereof, and may be implemented as a computer system or other processing system. In one embodiment, processor 204 is implemented as one or more computer systems. In another embodiment, the processor 204 is mainly implemented based on hardware using, for example, hardware components such as application specific integrated circuits (ASICs). Implementation using a state machine based on hardware with the implementation of the described functions is obvious to specialists in this field of technology. In yet another embodiment, processor 204 is implemented using a combination of both hardware and software.

3 is a block diagram illustrating a transceiver 104 in more detail. The transceiver 104 includes a transmitter 112, a receiver 110, a measurement element 302, a processor 304, a memory 306, a data receiver 310, and a data source 312. In operation, receiver 110 receives signal 118 and transmits it to data receiver 310. The receiver 310 data can be any element that uses data, such as codecs, modems, digital signal processors, and the like. Receiver 110 may perform certain tasks, such as demodulation, in signal 118, as is well known in the art.

The measuring element 302 performs certain measurements of the parameters of the signal 118, as described in detail below. For example, these measurements include the measurement of fading speed (SZ). In a preferred embodiment, the measuring element 302 includes an SNR measurement circuit 314. The SNR measurement circuit 314 obtains the SNR measurements of the received signal 118. The circuits that perform these functions are well known in the art. These measurement results are transmitted to a transmitter 112 and / or data source 312 for transmission as part of a signal 116. These measurements are transmitted to a processor 304, which may be any processor known in the art or developed in the future. The processor 304 uses memory 306 to store data, such as measurement results, and other values, such as thresholds, for comparison with these measurement results.

A data source 312 generates data for transmission. Data source 312 may include elements such as, for example, codecs, modems, digital signal processors, and the like, as is well known in the art. Transmitter 112 receives data from data source 312 and performs modulation before transmitting signal 116. Transmitter 112 also includes a variable gain amplifier 308 to amplify the signal before transmitting to generate signal 116. The gain of amplifier 308 is controlled by processor 304.

Figures 4-6 are flow charts illustrating the operation of the present invention in accordance with a preferred embodiment. 4 depicts the operation of an internal power control loop of the present invention. The function of the internal power control loop is to control the power of the signal transmitted by the transmitter 112. In a preferred embodiment, the power of the transmitted signal is adjusted in accordance with the power level of the signal received at the receiver 108, as described below.

Transmitter 112 transmits signal 116 through channel 122. Signal 116 is received by receiver 108. The process begins by measuring the power of signal 116 by measuring element 202, as shown in step 402. In a preferred embodiment, measuring element 202 measures the signal-to-noise ratio (SNR) of signal 116. More specifically, according to the present invention, the Eb / No value is measured, where Eb is the energy per bit, and No is the noise density in units of power / cycle. Of course, other measures of signal power may be used without departing from the scope of the present invention. In a preferred embodiment, the SNR is measured for each frame of received data.

In the communication system 100, a predetermined SNR level, referred to as an "SNR threshold", is associated with the receiver 108. The SNR threshold represents the minimum SNR at which signals must be received by the receiver 108 in order to guarantee signal quality. The SNR threshold may be selected in accordance with methods that are well known in the art. One of these methods is the choice of SNR, which will maintain the value of data errors below a certain percentage, for example one percent. At step 404, the receiver 108 compares the SNR measured at step 402 with the SNR threshold.

If the measured SNR is lower than the SNR threshold, then the transmitter 106 of the transceiver 102 transmits an “increase power” command to the transceiver 104, as shown in step 406. In a preferred embodiment, the command is transmitted as part of the signal 118 via channel 122. In response, the transmitter 112 increases the power signal 116 by a predetermined amount, defined as the "gain" of the inner loop or the "gain of the inner loop". In a preferred embodiment, the magnitude of the gain of the inner loop and the magnitude of the gain of the signal used by the amplifier 308 are stored in the memory 306. The magnitude of the gain of the signal is processed by the processor 304.

If the measured SNR exceeds the SNR threshold, then the transmitter 106 of the transceiver 102 transmits a “reduce power” command to the transceiver 104, as shown in step 108. In response, the transmitter 112 reduces the signal power 116 by the gain of the inner loop. In any case, the process resumes at step 402.

5 depicts the operation of an external power control loop according to the present invention (also referred to as an “outer loop”). The function of the external power control loop is to adjust the SNR threshold of the receiver 108. In a preferred embodiment, the SNR threshold is adjusted in accordance with the quality of the received signal. In a preferred embodiment, the signal quality is taken into account not only for the current frame, but also for a certain number of previous frames. Also in a preferred embodiment, the measure of signal quality used is the presence of one or more error events, for example, a frame error rate (FER) is used. However, other signal quality measures, such as parity, may be used without departing from the scope of the present invention. In addition, other methods of calculating the signal quality history can be used, for example, using average values and weighted average values.

A common type of error is the batch type. Batch errors are short in duration. Typically, the duration of a burst error is less than the period of the inner loop. Therefore, the internal circuit cannot compensate for these errors. For this reason, it is desirable to isolate the internal circuit from the effects of packet errors. Batch errors are characterized by the presence of errors in many consecutive frames. The outer loop uses this feature to detect burst errors. When the outer loop detects errors in a plurality of consecutive frames, it determines that a burst error has occurred. When a burst error is detected, the outer loop does not change the SNR threshold of the inner loop. The outer loop changes the SNR threshold of the inner loop only in response to non-packet type errors, thereby isolating the inner loop from packet errors.

According to figure 5, the procedure begins by taking measurements of a value indicating the presence of errors, for example, FER, as shown in step 502. It is determined whether there are errors in the current frame using the results of such measurements, as shown in step 504. If there are no errors in the current frame, as indicated by the branch “no” at step 504, the transceiver 102 reduces the SNR threshold by a predetermined amount, as shown at step 506. However, if errors are present in the current frame, as indicated by the branch “yes” at step 504, then it is analyzed prehistory the quality signal of the received signal, as shown in step 508. In a preferred embodiment, the error history contains a predetermined number of previous frames N. Of course, the error history can be selected by other methods without going beyond the scope of the present invention. The error history is stored in memory 206. If some of the previous N frames contain an error, then the transceiver 102 reduces the SNR threshold by the gain of the external circuit, as shown in step 506, depending on the desired frame or time delay, as described below.

However, if the preceding N frames are error free, then the transceiver 102 increases the SNR threshold, as shown in step 510. In the preferred embodiment, two change values are used: one to decrease the SNR threshold and the other to increase the SNR threshold. The magnitude of the change to reduce the SNR threshold is small, so that the SNR threshold and due to the action of the internal circuit, the power of the transmitted signal decreases gradually under transmission conditions without errors. On the contrary, the magnitude of the change to increase the SNR threshold is large so that the SNR threshold and due to the action of the internal circuit, the power of the transmitted signal increases rapidly in the conditions of transmission without errors.

In addition, it was found that in the General case, it is undesirable to quickly change the SNR threshold for a certain number of frames after an increase has been made, regardless of the presence or absence of errors, at least in some systems. Therefore, in one embodiment, the initial SNR increase is made when a frame error is detected after a certain number of frames without errors, as described above, but during the pre-selected number of frames Z after this adjustment, an additional increase is not allowed. That is, the detection or absence of frame errors does not provide a mechanism for selecting additional increases in the threshold value before the expiration of Z frames or frame periods after the increase. This is shown by optional step 512, between the quality history check step 508 and the threshold adjustment step 510. At 512, a check is made whether or not Z data frames are processed after the last increase in the SNR threshold. The frame count for this processing step is initially set to Z, so that when the adjustment is requested for the first time, it is executed as shown by set / reset step 514. Subsequent adjustments will then be determined from the frame count.

Whenever Z frames are not yet processed or not skipped, it is allowed to reduce the SNR threshold by a fairly small amount or at a low speed for each of Z frames, as shown in step 516. That is, during or at the end of each frame period, the threshold level SNR receives a negative increment or decreases by a small percentage or a value of the order of 0.004 dB. It will be apparent to those skilled in the art that other values may be used, including 0 dB, if necessary. Processing then returns to step 512, where measurements continue, and so on. After reaching the required number of pre-selected frames Z, the SNR threshold again increases at step 510 (or decreases at step 506) instead of a negative increment at step 516. If the SNR threshold increases, the frame count used at step 512 is reset to zero, and the counting process starts anew until Z frames pass again.

This process of gradual reduction or period allows the system to "establish" before further actions are carried out, and guarantees a more predictable and reproducible response to signal states. In addition, due to the batch nature of some errors and the minimum delay in the implementation of power increase commands that occur in some systems (satellite) or in situations, the implementation of short power change requests will not lead to the desired result. However, waiting for several frames over time will reduce the amount of power used.

After the pre-selected number of Z frames has passed, the SNR threshold adjustment occurs as before. Error detection again causes an increase in the SNR threshold, provided that the previous N frames do not contain errors. In a preferred embodiment, Z is selected to be six frames after generating a frame or starting the SNR threshold increase procedure, during which there is no further increase, but a gradual decrease. However, it should be clear to those skilled in the art that other values may be selected in accordance with known reaction parameters of the communication system in which the invention is used.

6 is a flowchart illustrating the operation of an internal loop with variable gain of a dual-loop power control, in accordance with a preferred embodiment of the present invention. At 602, the receiver 108 measures the rate of fading of the signal received from the transceiver 104A. In accordance with a preferred embodiment, the receiver 108 measures the SNR of the received signal several times during each frame to form a sequence of measurement results. This sequence is fed into the high-pass filter to detect rapid changes in the SNR, which indicate the presence of rapid fading. The output of the high-pass filter, which carries information about the fading speed, is compared with a predetermined threshold of the fading speed, as shown in step 604.

If the fading rate does not exceed a threshold, as indicated by the no branch from step 604, the fading is not fast enough. In this case, the gain of the inner loop is set to a first predetermined gain level G1, as shown in step 606.

If the high-frequency component of the fading exceeds a threshold, as indicated by the yes branch in step 604, the fading is qualified as fast. In this case, the gain of the inner loop is set to a second predetermined gain level G2, as shown in step 608. In any case, processing is resumed in step 602.

In a preferred embodiment, the first gain level G1 is much larger than the second gain level G2. In other words, the gain of the inner loop used in fast fading is significantly less than the gain of the inner loop used otherwise. The result is that with fast fading, the power control loop does not try to track fast fluctuations in the signal power level caused by fast fading, but instead tracks slower fluctuations in the signal power level caused by slower fading. In one embodiment, G1 is approximately 0.5 dB, and G2 is approximately 0.1 dB.

In one embodiment, the user terminal detects fast fading in a signal transmitted from the gateway to the user terminal. In this embodiment, the user terminal notifies the state of fast fading to the gateway, which in response provides gain control of the internal power control loop. 1, a fast fading in the signal 116 is detected by the transceiver 102 in step 604. The transceiver 102 detects a fast fading in the signal 116 by estimating fluctuations in the SNR, as described in detail above. Fast fading is detected by assessing SNR. The transmitter 106 then transmits a command to the receiver 110 to adjust the gain of the inner loop. In accordance with this command, the transceiver 104 adjusts the gain of the inner loop in steps 606 and 608.

In another embodiment, a decision is made in the gateway that there is a fast fading in the signal transmitted from the gateway to the user terminal when a fast fading of the signal transmitted by the user terminal to the gateway is detected. 1, the fading rate of signal 116 is determined in transceiver 104 by evaluating the SNR fluctuation in signal 118 in steps 602 and 604, as described in detail above. Based on this estimate, the transceiver 104 then adjusts the gain of the inner loop in steps 606 and 608.

III. Conclusion

The above description of preferred embodiments is intended to enable any person skilled in the art to make or use the present invention. Various modifications to the presented embodiments are fairly obvious to those skilled in the art, and the general principles defined herein can be applied to other embodiments without further inventions. Thus, the present invention is not limited to the embodiments presented in the present description, but should correspond to the widest scope consistent with the principles and new features disclosed in the present description.

Claims (20)

1. A device for controlling power in a wireless communication system, comprising means connected to a first station for measuring a signal-to-noise ratio for a signal transmitted by a second station, said signal comprising a plurality of frames, means for adjusting a power of a transmitted signal as a function of gain circuit, signal-to-noise ratio and threshold of the signal-to-noise ratio, means connected to the first station for measuring the quality of the received signal, means for regulating the threshold of the signal-to-noise ratio al / noise, as a function of signal quality and the signal quality threshold, containing means for increasing the threshold of the signal to noise ratio when the current frame has an error and a predetermined number of previous frames have no errors, with a predetermined minimum period between increases and means for reducing otherwise, the means connected to the first station for measuring the rate of fading of the signal and the means for adjusting the loop gain as a function of the rate of fading and horns of speed of fading. 2. The device according to p. 1, characterized in that the threshold of the signal-to-noise ratio decreases by a pre-selected small amount during the mentioned minimum period. 3. The device according to claim 1, characterized in that said means for increasing comprises means for increasing the threshold of the signal-to-noise ratio by a predetermined amount and said means for decreasing comprises means for decreasing the threshold of the signal-to-noise ratio by a value significantly smaller than said predetermined value. 4. A device for controlling power in a wireless communication system, comprising means connected to a first station for measuring a signal-to-noise ratio for a signal transmitted by a second station, means for controlling a transmitted signal power as a function of loop gain, signal-to-noise ratio, and the signal-to-noise ratio threshold, means connected to the first station for measuring the quality of the received signal, means for regulating the signal-to-noise ratio threshold as a function of signal quality and quality threshold and a signal, means connected to the first station for measuring the fading speed of the signal and means for adjusting the loop gain as a function of fading speed and the threshold of fading, comprising means for setting the loop gain to the value of the first loop gain when the fading speed is lower said threshold of fading speed and means for setting the loop gain to the value of the second loop gain when said fading speed above the threshold of fading speed. 5. The device according to claim 4, characterized in that the second loop gain is much less than the first loop gain. 6. A device for controlling power in a wireless communication system, comprising means connected to a first station for measuring a signal-to-noise ratio for a signal transmitted by a second station, said signal comprising a plurality of frames, means for adjusting a power of a transmitted signal as a function of gain contour, signal-to-noise ratio and signal-to-noise ratio threshold, means connected to the first station for measuring the quality of the received signal, means for regulating the threshold of the signal-to-noise ratio al / noise, as a function of signal quality and the signal quality threshold, containing means for increasing the threshold of the signal to noise ratio when the current frame has an error and a predetermined number of previous frames have no errors, with a predetermined minimum period between increases and means for reducing otherwise, the means connected to the second station for measuring the fading rate of the additional signal transmitted by the first station and means for adjusting the gain contour as a function of fading speed and fading threshold. 7. The device according to p. 6, characterized in that the threshold of the signal-to-noise ratio decreases by a pre-selected small amount during the mentioned minimum period. 8. The device according to p. 6, characterized in that said means for increasing comprises means for increasing the threshold of the signal-to-noise ratio by a predetermined amount, and said means for decreasing comprises means for decreasing the threshold of the signal-to-noise ratio by a value significantly lower, than the mentioned predetermined value. 9. A device for controlling power in a wireless communication system, comprising means connected to a first station for measuring a signal-to-noise ratio for a signal transmitted by a second station, means for controlling a transmitted signal power as a function of loop gain, signal-to-noise ratio, and the signal-to-noise ratio threshold, means connected to the first station for measuring the quality of the received signal, means for regulating the signal-to-noise ratio threshold as a function of signal quality and quality threshold and a signal, means connected to the second station for measuring the fading speed of an additional signal transmitted by the first station, and means for adjusting the loop gain as a function of fading speed and the fading threshold, comprising means for setting the loop gain to the value of the first gain contour when the fading speed is lower than the mentioned threshold of fading speed and means for setting the loop gain to the value of the second contour when the fading speed is higher than the fading speed threshold. 10. The device according to p. 9, characterized in that the second loop gain is much less than the first loop gain. 11. A method of controlling power in a wireless communication system, comprising the steps of measuring in a first station a signal-to-noise ratio for a signal transmitted by a second station, said signal comprising a plurality of frames, adjusting a transmitted signal's power as a function of loop gain, signal-to-noise ratio, and the signal-to-noise ratio threshold, measuring the quality of the received signal at the first station, adjusting the signal-to-noise ratio threshold as a function of signal quality and the signal quality threshold, including the steps of the threshold value of the signal-to-noise ratio when the current frame has an error, and the predetermined number of previous frames have no errors, with a predetermined minimum period between increases and a decrease in the signal-to-noise ratio threshold otherwise, measuring the signal fading speed and regulation at the first station loop gain as a function of fading speed and fading threshold. 12. The method according to p. 11, characterized in that the threshold of the signal-to-noise ratio is reduced by a pre-selected small amount during the aforementioned minimum period. 13. The method according to p. 11, characterized in that said step of increasing includes increasing the threshold of the signal-to-noise ratio by a predetermined amount, and said step of decreasing includes reducing the threshold of the signal-to-noise ratio by an amount significantly less than said predetermined value. 14. A method of controlling power in a wireless communication system, comprising the steps of measuring in a first station a signal-to-noise ratio for a signal transmitted by a second station, adjusting a transmitted signal's power as a function of loop gain, signal-to-noise ratio and signal-to-noise ratio threshold, measurements in the first station the quality of the received signal, regulating the threshold of the signal-to-noise ratio, as a function of signal quality and the threshold of signal quality, measuring the speed of the signal fading in the first station and adjusting loop gain as a function of fading speed and fading threshold, including the steps of setting the loop gain to the value of the first loop gain when the fading speed is lower than the fading threshold and setting the loop gain to the second loop gain when the fading speed is higher mentioned threshold fading speed. 15. The method according to p. 14, characterized in that the second loop gain is much less than the first loop gain. 16. A method of controlling power in a wireless communication system, comprising the steps of measuring in a first station a signal-to-noise ratio for a signal transmitted by a second station, said signal comprising a plurality of frames, adjusting a transmitted signal power as a function of loop gain, signal-to-noise ratio, and the signal-to-noise ratio threshold, measuring the quality of the received signal at the first station, adjusting the signal-to-noise ratio threshold as a function of signal quality and the signal quality threshold, including the steps of the value of the signal-to-noise ratio threshold, when the current frame has an error, and the predetermined number of previous frames have no errors, with a predetermined minimum period between increasing and decreasing the signal-to-noise ratio threshold otherwise, measuring the additional signal fading speed in the second station, transmitted by the first station and controlling the loop gain as a function of fading speed and fading threshold. 17. The method according to p. 16, characterized in that the threshold of the signal-to-noise ratio is reduced by a pre-selected small amount during the mentioned minimum period. 18. The method according to p. 16, characterized in that said step of increasing includes increasing the threshold of the signal-to-noise ratio by a predetermined amount, and said step of decreasing includes reducing the threshold of the signal-to-noise ratio by an amount significantly less than said predetermined value. 19. A method of controlling power in a wireless communication system, comprising the steps of measuring in a first station a signal-to-noise ratio for a signal transmitted by a second station, adjusting a transmitted signal power as a function of loop gain, signal-to-noise ratio and signal-to-noise ratio threshold, measurement in the first station the quality of the received signal, adjusting the threshold signal-to-noise ratio, as a function of signal quality and the threshold of signal quality, measuring in the second station the fading speed of the additional signal transmitted by the first station and controlling the loop gain as a function of fading speed and the fade threshold, including the steps of setting the loop gain to the value of the first loop gain when the fade speed is lower than the fading threshold and setting the loop gain to the second coefficient loop gain when the fading rate is higher than said fading rate threshold. 20. The method according to p. 19, characterized in that the second loop gain is much less than the first loop gain.

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